So long that licensed hardware meets a minimum spec and always maintains a minimum performance level, then there shouldn't be a problem. We could easily live with upgradeable consoles, or at least scalable consoles. It's sort of like that with the PSP and Vita (Playing PSP on Vita: better analogue stick, secondary stick support mapped to the face buttons, better performance etc).
I can't imagine the next gen supporting it. Maybe the one after will.
It could also allow the base model to be sold at a lower price, giving more people the chance to jump on board, which is good news for everyone.
Anyway, my wish list includes
-support for 4k (don't need it now, will in 6 years, maybe)
-everything to be released simultaneously on Blu Ray and digital (fully expect this to happen)
-a lot more ram for those highly detailed, beautiful, indistinguishable from real life open end environments. Can't claim to know too much about RAM in consoles but from what I have read I believe it would be beneficial for the ram not to be pooled like it has on the ps3.
-I want a big glossy sexy PS4 console, available in black and white from day one. (Highly doubt this because, unlike apple, sony cannot guarantee that they shift decent amounts of either colour, if they misjudge demand they are in a whole world of trouble)
Please chime in with your wish lists. And feel free to rip mine to pieces.